Cable insulation removing tool



April 16, 1968 R. G. HoRRocKs CABLE INSULATION REMOVING TOOL Filed July 17, 1967 United States Patent O 3,377,891 CABLE INSULATION REMOVING TOOL Raymond G. Horrocks, Parkview, Ohio, assigner to The Scott & Fetzer Company, Cleveland, Ohio, a corporation of Ohio Filed July 17, 1967, Ser. No. 653,977

9 Claims. (Cl. 819.5)

ABSTRACT F THE DISCLOSURE This invention relates generally to the art of removing insulation and semi-conductive material from cable used to conduct high voltage electric current and is particularly concerned with a new hand tool which is simple in construction, which may be used to remove insulation from cables of different diameters and which is easy to operate. In one form it may be used to limit the length of cable from which the insulation is removed.

Bfzckgroundvf the invention Prior workers in the art have proposed various devices for removing insulation from cables which are to be used in carrying high voltage current. As illustrative of this class of devices, I mention the following United States Letters Patents: Matthews, No. 3,204,495; Ghiglia, No. 2,897,702; Blonder No. 2,903,064; Edwards, No. 2,120,- 398 and my Patent No. 3,255,629.

While the devices of each of those patents is capable of removing insulation from cables, they possess certain disadvantages. The Edwards and Blonder devices make circumferential cuts through the insulation at right angles to the axis of the cable, thus severing a short axial length of insulation from the main body thereof. Such a length of insulation is difficult to remove from the cable. Edwards proposed to cut this short length of insulation longitudinally to make its removal easier and required two cutters to accomplish those purposes. Both the Edwards and Blonder devices consist of a considerable number of parts which, in itself, is a disadvantage.

The Ghiglia device lacks any means for regulating the depth of the cut of insulation and is not conducive to easy operation. The Matthews device employs springs to urge the cutting tool into the insulation and lacks means for determining the depth or uniformity of the depth of cut of the insulation. The device of my patent has been quite satisfactory in commercial use but is particularly adapted for tapering the insulation. It cannot remove the insulation at substantially right angles to the cable.

Summary of the invention Brief description of the drawings In the drawings accompanying and forming a part of this specitication:

FIG. 1 is a perspective view of one form of tool ernbodying the present invention and showing a cable about 7 to be inserted therein;

3,377,391 Patented Apr. 16, 198

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FIG. 2 is a fragmentary view of parts of FIG. l showing the end of the bare conductor and severed turns of the insulation;

FIG. 3 is a plan view of the front end of the tool of FIG. l with parts removed; and

FIG. 4 is a longitudinal, sectional view, taken on line 4 4 of FIG. 1, certain parts being shown in elevation.

The preferred form of the present invention, as shown in FIGS. 1 to 4, includes a cylindrical body 1 provided with a longitudinal bore 3 and, if desired, with an oiiset longitudinal opening 5. A cylindrical bushing 7 is rotatably mounted in bore 3 and is restrained against longitudinal movement toward the front end of the tool by flange 9 at the rear end of the bushing and is permitted to rotate in the body but is restrained against moving rearwardly by set screw 11 which extends into circular recess 13 in the outer surface of the bushing.

It will be understood that the inner cylindrical surface of bushing 9 should be only slightly larger than the outside diameter of the insulation 10 which is to be removed from cable 11. For example, the space between the outer surface of the insulation and the inner surface of bushing 9 should not be greater than about .010 inch. A greater clearance might result in nicking of the conductor or incomplete cutting of the insulation.

The front face of the body 1 is recessed transversely, as at 17, to receive a cutting tool 19 and is also recessed, as at 21, to receive a bar 23. A land 24 on the front face of the body 1 separates and partly defines recesses 17 and 21. As will be noted from FIGS. 3 and 4, the rear surface of recess 17 is inclined at a small angle, for example, up to about 3 to the front face of the body 1. This angularity has been found to afford a good combination of ease of cutting and depth of cut of the insulation. A greater angle tends to make a deeper cut and increase the friction of the insulation against the bar while a smaller angle tends to make a thinner cut and requires more time to remove a given length of insulation.

The cutting blade 19 is adjustably secured to the front face of body 1, as by a set screw 29, which is in slot 31 in the tool. The blade bears against the outer edge 30 of recess 17 and the cutting edge 33 of the blade is positioned just out of engagement with the opposed side of land 24. The edge 33 of blade 19 lies on a diameter of the bushing and of the cable within Ithe bushing. As is shown in FIG. 3, the blane is adjusted transversely of the bushing so as to extend across the insulation and almost into contact with the conductor within the insulation. The tool may lbe adjusted to the precise position desired by putting the cable into the bushing and then adjusting the tool transversely until the corner of the cutting edge is just out of contact with the conductor.

The rear surface of recess 2'1 on which the bar 23 is disposed is substantially parallel to the front face of the body but is positioned a short distance forwardly of the cutting edge 33 of the blade 19, for example, not more than about 1/32 inch and is secured in position by screws 34. The bar 23 acts as a stop for the insulation on the conductor and thus limits the axial depth of the cut of the insulation vto the distance between the rear face of bar 23 and the cutting edge 33. A greater distance permits a thi-cker eut and a smaller distance permits a thinner cut. A cut -of about /32 inch is a good practical cut.

The operation of the tool just described wi'll be readily understood by those skilled in the art, but, brieiiy stated, it consists of placing an insulated cable in 'bushing 7 with its forward end just clearing the cutting blade 19. The cutting blade 19 is then adjusted transversely of the body 1 until the corner of the cutting edge lies in the desired -cl-ose proximity of the conductor. Then relative rotation of the cable and body 1 causes the cutting blade to sever the insulation in turns each having an axial length or thickness equivalent to the space between the rear surface of bar 23 and the cutting edge 33.

The above described inclination of the cutting blade gives the unexpected results that less force is required to move the body and cable relatively both axially and rotationally. The tool enters the insulation more readily and urges the cable axially than would be the case if the blade were perpendicular to the cable.

When the desired amount of -insulation has been cut in this spiral form in this manner, the cable and body may be urged axially away from each other and rotated relatively which will result in severing the turn of insulation adjacent to the main body of insulation. The severed portion lof the insulation may be readily removed from the cable by manually removing such insulation over the free end of the cable while the cable is retained in the body 1 lby bar 23, or by holding the cable and moving the body forwardly.

If desired, the body 1 may be provided with a cable stop as is shown in FIGS. l .and 4. This illustrated stop includes a rod 35 which is movable endwise in longitudinal opening in the body. At the front end of rod 3S an arm 37 projects laterally to a position intersecting the projection of the conductor. The rod is grooved, longitudinally, as at 36, to receive a set screw 39 and is preferably marked to indicate the distance between the rear side of arm 37 and the cut-ting edge 33. By determining the length of the cable from which the insulation is to be removed and adju-sting the rod 35 so that the rear face of arm 37 is the desired distance from the cutting edge 33 and tightening set screw 39, the cutting tool and cable may be rotated relatively until the conductor contacts the arm 37, whereupon further relative movement of the body and cable will result in severing the previously cut turns of the insulation.

Having thus described this invention in such full, clear, concise and exact terms as to enable any person skilled in the art to which it pertains to make and use the same, and having set forth the best mode contemplated of carry ing out this invention, I state that the subject matter which I regard as being my invention is particularly pointed out and distinctly claimed in what is claimed, it being understood that equivalents or modification of, or substitutions for, parts of the above specifically described embodiment of the invention may be made Without departing from lthe scope of the invention as set forth in what is claimed.

What is claimed is:

1. A tool for removing insulation and semi-conducting material from an electrical conductor cable which comprises:

(a) a cylindrical body having a central axial bore, a bushing in said bore having an axial passage only slightly larger in diameter than the outside diameter of 4the insulated cable and means to secure the bushing in the body against relative endwise movement,

(b) a cutting blade secured to the front face of the `body and having a cutting edge positioned on a diameter of the bushing and extending across the bushing and insulation to a point just short of making contact with the conductor, and

(c) a bar secured to the front face of the body and extending across part of the bore and bushing and having an edge substantially parallel to but spaced apart from the cutting edge of the blade, the rear surface of said bar being positioned forwardly of the cutting edge of the blade by a distance equal to the desired axial thickness of insulation to be removed from a cable at each turn of the body and cable relatively.

2. The combination of elements set forth in claim 1 in which the cutting blade is inclined to make a small included angle with the front face of the body.

3. The combination of elements set forth in claim 2 in which the said included angle of the cutting blade and body is less than about 3.

4. The combination of elements set forth in claim 3 in which the distance between the rear face of the bar and the cutting edge of the tool is less than about 1/32 inch.

5. The combination of elements set forth in claim 2 in which the said body is provided with an offset longitudinal opening and a rod is adjustably positioned therein and is provided with an arm to engage the end of a conductor from which insulation has been removed.

6. The combination of elements set fort-h in claim 3 in which the body is provided with an offset longitudinal opening and a rod is adjustably secured therein and is provided with an arm to be engaged by the end of a conductor from which the insulation has been removed.

7. The combination of elements set forth in claim 1 in which the distance between the rear surface of said bar and the cutting edge of the tool is less than about 1/32 inch.

8. The combination of elements set forth in claim 7 in which the body is provided with an oest longitudinal opening and a rod is -adjustably positioned therein and carries an arm at its forward end which is engageable by the end of a conductor from which insulation has been removed.

9. The combination of element-s set forth in claim 1 in which the cylindrical body has an odset longitudinal opening and a rod secured in lsaid opening and is provided with an arm at its forward end to be engaged by the end of the conductor from which insu-lation has been removed by lthe cutting edge. Y

References Cited UNITED STATES PATENTS 2,566,434 9/1951` Toth et al. 30-90.6 X 2,897,702 8/1959 `Ghiglia 81--9.5 3,204,495 9/1965 Matthews til-9.5

FOREIGN PATENTS 763,853 2/1957 Great Britain.

MLTON S. MEHR, Primary Examiner. 

